Skye Gyngell's restaurant Spring, set in a 19th-century drawing room in Somerset House, is perhaps London's prettiest. The chef, who was previously in charge of the kitchen at the Michelin-starred Petersham Nurseries, dishes up a daily changing menu from seasonal ingredients. But without a vegetable patch she has to make do with ingredients that come from slightly further afield - Fern Verrow on the borders of Wales and Herefordshire, to be precise. She made a pledge to the farm to take everything they produce; and so, to avoid food waste, she lays on a second menu daily: the Scratch Menu. Named after a 'scratch tea' from her native Australia, the three-course menu uses up any ingredients which might otherwise go to waste or are overlooked - from asparagus tops and cauliflower leaves to leftover milk that's been heated for coffee. Every morning she takes a look in the fridge, and works out ways to turn the leftovers into delicious and nutritious meals that are first-class enough to satisfy Spring's discerning foodie clientele. Here, Gyngell talks to Condé Nast Traveller about the importance of making a political stand, zero-waste cooking, and how to cook with scraps.